Role of optical aberrations in 3D space perception: Implications for Keratoconus

University Of California Berkeley, Berkeley CA

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Abstract

DESCRIPTION (provided by applicant): The following is a summary of Dr. Sangeetha Metlapally's Mentored Clinical Scientist Research Career Development Award (K23) application. Keratoconus is a progressive, degenerative condition characterized by corneal thinning and steepening, leading to increased optical aberrations. The socio-economic liability and impact on the quality of life of visual deficits in this condition is disproportionate, affecting predominanty young adults during prime earning and child-rearing years. Increased magnitudes of optical higher-order aberrations (HOAs) and inter- ocular asymmetries in the aberrations are common, and could potentially lead to problems with binocular space perception, which is not well understood in this subject population. Current clinical management paradigms concentrate heavily on maximizing monocular high-contrast visual acuities, which do not address losses in stereoscopic depth perception, as seen in our preliminary data. The planned research program addresses the issue of irregular corneal optics leading to impaired binocular space perception in keratoconus or post-LASIK. The results may apply to the qualitatively similar effects of irregular optics on vision due to aberrations in other conditions like pellucid marginal degeneration, post-LASIK keratectasias or following corneal transplants. There are three independent optical factors that could contribute to the loss of stereoscopic depth perception. Inter-ocular asymmetries in lower-order aberrations (LOAs) and HOAs could cause inter-ocular contrast differences reducing stereo-acuity. Further, aniseikonia, due to refractive anisometropia corrected with spectacles, would produce distortions of perceived space and interfere with stereopsis. Thirdly inter-ocular phase differences produced by aberrations could produce false-binocular matches that would lower the strength of disparity signals for stereo-depth. We hypothesize, therefore, that some or all of the above, resulting from increased aberrations and inter-ocular optical asymmetries can lead to loss of stereoscopic depth perception and distortions in the three dimensional perception of space. Our goal is to compare performance with contact lens corrections, which minimize the contribution of HOAs, and spectacle lens corrections, by way of investigating the influence of disease-related or surgically-induced HOAs on stereo-depth perception. The proposed research is novel and innovative as it uses powerful, validated tools to collect and analyze optical wave front data and examines the yet unknown effects of irregular optics on binocular space perception. We hope that the proposed aims will lead to a better understanding of the inter-relationships between irregular optics and binocular vision, and directly translate to optical or other management strategies in the clinic that will better serve to improve spatial vision in individuals with keratoconus or irregular corneal optics.